Palynology and age of the upper Blomidon Formation, Fundy basin, Nova Scotia

Fowell, Sarah J.; Traverse, Alfred

doi:10.1016/0034-6667(94)00147-c

Cited by 54 publications

(45 citation statements)

References 12 publications

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“…These results are consistent with the described occurrence of Triassic fossils above the lowermost CAMP flows of the Culpeper basin, Virginia (Kozur & Weems, 2005;Lucas & Tanner, 2007). In the Fundy basin, the TJB has been interpreted as occurring about 30-40 cm below the North Mountain basalt at Partridge Island (North Shore) where the last occurrence of some Triassic palynomorphs has been observed (Fowell and Traverse, 1995;Whiteside et al., 2007). Isotopic constraints on the age of the TJB includes a U/Pb single zircon age of 199.6 ± 0.3 Ma obtained on the Sandilands Formation in the Queen Charlotte Islands in western Canada (Pálfy et al, 2000).…”

Section: Timing Of Camp Versus T-j Boundary: Radioisotopic Dating Permentioning

confidence: 99%

40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias

Jourdan

Marzoli

Bertrand

et al. 2009

Lithos

107

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The Central Atlantic magmatic province (CAMP) is one of the largest igneous provinces on Earth (>10 7 km²) and spanning four continents. Recent high-precision 40 Ar/ 39 Ar dating of mineral separates has provided important constraints on the age, duration, and geodynamic history of CAMP. Yet, the North American CAMP is strikingly under-represented in this dating effort. Here we present 13 new statistically robust plateau, mini-plateau and isochron ages obtained on plagioclase and sericite separates from lava flows from the Fundy (n = 10; Nova Scotia, Canada) and Hartford and Deerfield (n = 3; U.S.A.) basins. Ages mostly range from 198.6 ± 1.1 to 200.1 ± 1.4 Ma (2σ), with 1 date substantially younger at 190.6 ± 1.0 Ma. Careful statistical regression shows that ages from the upper (199.7.0 ± 1.5 Ma) and bottom (200.1 ± 0.9 Ma) units of the lava pile in the Fundy basin are statistically indistinguishable, confirming a short duration emplacement (<< 1.8 Ma; ≤1 Ma). Three ages obtained on the Hartford (198.6 ± 2.0 Ma and 199.8 ± 1.1 Ma) and Deerfield (199.3 ± 1.2 Ma) basins were measured on sericite from the upper lava flow units. We interpret these dates as reflecting synemplacement hydrothermal activity within these units. Collectively, CAMP ages gathered so far suggest a short duration of the main magmatic activity (2-3 Ma), but also suggest the possibility of a temporal migration of the active magmatic centers from north to south. Such a migration challenges a plume model that would postulate a radial outward migration of the magmatism and is more compatible with other models such as the supercontinent global warming hypothesis. When compared to the age of the Triassic-Jurassic boundary, the filtered CAMP age database suggests that the onset of the magmatic activity precedes the limit by at least few hundred thousand years, therefore suggesting a causal relationship between CAMP and the end of Triassic mass extinction. An age at 191 Ma possibly suggests a minor CAMP late tailing activity (190)(191)(192)(193)(194) which has already observed for dykes and sills in Africa and Brazil. We speculate that, if real, this late activity can be due to a major extensional event, possibly heralding the oceanisation process at ~190 Ma. Comparison between high quality U/Pb and 40 Ar/ 39 Ar ages of pegmatite lenses from the North Mountain basalts confirms a ~1% bias between the two chronometers. This discrepancy is likely attributed to the miscalibration of the 40 K decay constants, in particular the electron capture branch.

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Section: Timing Of Camp Versus T-j Boundary: Radioisotopic Dating Permentioning

confidence: 99%

40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias

Jourdan

Marzoli

Bertrand

et al. 2009

Lithos

107

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“…At its type section, the Partridge Island Member consists of about 1 m of interbedded red, purple, grey, and black (variegated) mudstone and minor carbonates that have proven critical to the interpretation of the end-Triassic extinction (e.g., Blackburn et al 2013). The unit contains pollen and spores at several levels, documenting the initial phase of the end-Triassic extinction (Fowell and Traverse 1995;Whiteside et al 2007;Cirilli et al 2009), has three modest iridium anomalies (Tanner and Kyte 2005; Tanner et al 2008;Kyte et al 2008), and contains the upper part of palaeomagnetic polarity chron E23r (Deenen et al 2011), which extends downward into the uppermost portion of the White Water Member (see Appendix). Based on zircon U-Pb dates, the age of the Partridge Island Member is latest Rhaetian at 201.564±0.015 Ma (Blackburn et al 2013).…”

Section: White Water Membermentioning

confidence: 99%

Stratigraphic and temporal context and faunal diversity of Permian-Jurassic continental tetrapod assemblages from the Fundy rift basin, eastern Canada

Sues

Olsen

2015

atgeol

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The Fundy basin in Nova Scotia and New Brunswick is the largest exposed rift basin of the Newark Supergroup and also extends beneath the Bay of Fundy. Its strata can be divided into four tectonostratigraphic sequences (TS). TS I is represented by the probably Permian Honeycomb Point Formation and possibly the Lepreau Formation. TS II includes the Wolfville Formation with the probably Middle Triassic Economy Member and the early Late Triassic Evangeline Member. These members have yielded markedly different assemblages of continental tetrapods. TS III comprises most of the Blomidon Formation, which is Norian to Rhaetian in age. The Blomidon Formation has yielded few skeletal remains of tetrapods to date but many tetrapod tracks. TS IV includes the late Rhaetian top of the Blomidon Formation and the McCoy Brook Formation, which overlies the North Mountain Basalt and is latest Rhaetian and earliest Jurassic (Hettangian) in age. The McCoy Brook Formation has yielded a diversity of continental tetrapods and lacks any of the characteristic Late Triassic forms. Recent work has correlated the Global Boundary Stratotype Section and Point (GSSP) for the base of the Jurassic (Hettangian) to a level well above the North Mountain Basalt. Thus most of the tetrapod fossils from the McCoy Brook Formation are latest Rhaetian in age, but the higher horizon with skeletal remains of sauropodomorph dinosaurs may be earliest Hettangian in age. The Fundy basin preserves the only known, stratigraphically tightly constrained record of the profound biotic changes in continental ecosystems across the Triassic-Jurassic transition.

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“…In the Jacksonwald syncline of the Newark basin, Olsen et al (2002b) place this boundary within 10 m to 15 m of the base of the Orange Mountain Basalt. In the Fundy basin, at Partridge Island, this transition is placed just 20 cm to 30 cm below the base of the North Mountain Basalt (Fowell and Traverse, 1995;Olsen et al, 2005).…”

Section: Palynostratigraphic Constraintsmentioning

confidence: 99%

The nonmarine Triassic–Jurassic boundary in the Newark Supergroup of eastern North America

Lucas¹,

Tanner²

2007

Earth-Science Reviews

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For the last three decades, the position of the Triassic-Jurassic boundary (TJB) in nonmarine strata has largely been based on its palynostratigraphic placement just below the oldest basalts of the Central Atlantic magmatic province (CAMP) in the Newark Supergroup of eastern North America. This boundary, however, is demonstrably older than the TJB as it is defined in marine strata. Thus, the palynostratigraphic change used to place this TJB in the Newark most resembles a late Norian change in the European section and does not correspond to any palynological event at the marine-defined TJB. Conchostracan biostratigraphy suggests that the TJB is in the Newark extrusive zone above the oldest CAMP basalt, and vertebrate biostratigraphy is consistent with this placement of the TJB. Radioisotopic ages indicate that the TJB defined in marine strata is no older than 200 MA, but the oldest CAMP basalts of the Newark Supergroup consistently yield ages averaging about 201 Ma. Magnetostratigraphic correlation of the Newark section to the TJB section at St. Audrie's Bay in England also indicates that the onset of CAMP volcanism in the Newark Supergroup is older than the marine TJB. Correlations based on carbon and osmium isotopes are also consistent with this correlation. Thus, all data indicate that the TJB in the Newark Supergroup is above the lowest CAMP basalt in the Newark extrusive zone. Correct placement of the TJB in the Newark Supergroup allows key nonmarine and marine events to be sequenced across the TJB, indicating the following succession of events: crurotarsan ("thecodont") extinction, the palynofloral turnover in the Newark, the first CAMP eruptions, the extinctions of Rhaetian ammonites and conodonts, and the first appearance of Jurassic psiloceratid ammonites.

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Palynology and age of the upper Blomidon Formation, Fundy basin, Nova Scotia

Cited by 54 publications

References 12 publications

40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias

40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias

Stratigraphic and temporal context and faunal diversity of Permian-Jurassic continental tetrapod assemblages from the Fundy rift basin, eastern Canada

The nonmarine Triassic–Jurassic boundary in the Newark Supergroup of eastern North America

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